Albanian j. agric. sci. 2013;12 (3): 389-395

Agricultural University of Tirana

RESEARCH ARTICLE

(Open Access)

Seed Size Influence On Germination And Seedling Development Of Cowpea (Vigna unguiculata (L) walp) OLAYEMI IBUKUN EHONIYOTAN AND * KEHINDE STEPHEN OLORUNMAIYE* Department of Plant Biology, University of Ilorin, Ilorin, Nigeria

Abstract The effect of seed size on the germination and seedling development was carried out on four local varieties of cowpea (Vigna unguiculata (L) walp), oloyin,drum, ifebrown and local white. Each of the varieties were sorted into big and small seeds, 100 seeds each of both big and small seeds of the four Varieties were weighed and the average weights were calculated and recorded. Six seeds of each sort were planted in a plastic pot filled with sandy-loamy soil in three replicates. Results of the various parameters studied revealed that germination efficiency was similar in both big and small seeds of drum, oloyin and ifebrown but not in small seeds of local white, weights of 100 seeds from big seeds were much heavier than those of small seeds. Number of leaves, leaf length, leaf breadth, leaf area, stem height and dry weight, were consistently higher in cowpea plants from big seeds than the small seeds of all the varieties. Number of seeds per pod was higher in cowpea from big seeds in all the varieties except in drum where number of seeds was higher in plants from small seeds. In general, seedlings emerging from big seeds of all the cowpea varieties performed better in all the parameters studied than those emerging from smaller seeds. Keywords: cowpea, germination, seedling, size, vigna unguiculata,

1. Introduction Cowpea is an erect to sub-erect, or prostrate, climbing, glabrous, annual herb. The stems are somewhat square and ripped, often with violent nodes [11]. It belongs to the family Fabaceae, it is one of the most ancient crop known to man. Cowpea is botanically known as Vigna unguiculata (L) walp which in older refrences may be identified as Vigna sinensis (L). [5]. It is widely grown in Africa (with Nigeria and Niger Republic predominating), Brazil, West Indies, India, United States, Burma, Srilanka, Yugoslavia and Australia. The history of cowpea dates to ancient West African cereal farming, five to six thousand years ago, where it was closely associated with the cultivation of sorghum and pearl millet [11]. Cowpea is a heat-loving, drought tolerant crop with high protein content and lower soil fertility requirements than many other crops [2]. The seed coat can be smooth or wrinkled and of various colours including white, cream, green, buff, red, brown and black. Seed may also be speckled, mottled or blotchy. Many are also referred to as “eyed” (black-eye, pink-eye, purple hull, etc) where the white coloured hilum is surrounded by another colour [4]. Cowpea can be used at all stages of growth as a vegetable crop. The tender green leaves are an important food source in Africa and are prepared as

herb, like spinach. Immature snapped pods are used in the same way as snap beans, often being mixed with other foods. Green cowpea seeds are boiled as a fresh vegetable, or may be canned or frozen. Dry mature seeds are also suitable for boiling and canning [4]. Cowpea has been identified as an ideal summer cover crop for many areas which can both produce abundant biomass and fix substantial quantities of atmospheric nitrogen [3]. It was observed by [10] that less time was required for germination initiation of medium seeds and small seeds than big seeds of cowpea. However, germination percentage has a distinct advantage of larger over smaller seeds. Larger seeds showed early vigorous seedling growth as compared to smaller seeds [10]). Small seeds were reported to germinate earlier as well as higher germination index than large seeds in Turkish cultivars of chickpea (Cicer arietinum L.) under interactive study of seed size and NaCl [7]. In many cases one observes small or tiny seeds of cowpea which were sorted and thrown away germinated and produced fruits. It is therefore, the objective of this study to investigate the effect of seed size and seed weight on the germination and seedling development of some local cowpea varieties in Ilorin, Nigeria.

Correspondence: Kehinde Stephen Olorunmaiye; Department of Plant Biology, University Of Ilorin, Ilorin, Nigeria; Email: [email protected] (Accepted for publication )21 May 2013 ISSN: 2218-2020, © Agricultural University of Tirana

Ehoniyotan and Olorunmaiye

The data collected were subjected to analysis of variance (ANOVA) using SPSS 15 statistical package with their means separated by Duncan`s multiple range test (DMRT).

2. Materials and Methods Seeds of four varieties of cowpea (Vigna unguiculata) were purchased in Ilorin, Kwara State, Nigeria and were sorted into big and small sizes. The dry weights of 100 seeds of both big and small seeds of each variety were taken using mettler balance and the average recorded. The varieties used include; ‘Drum’, ‘local white’, ‘oloyin’ and ‘Ifebrown’. Twenty-four plastic pots used for planting were previously perforated to prevent water logging. The pots were filled with sandy-loam soil and arranged in four rows according to the number of varieties of cowpea and were labelled accordingly. Six seeds were sown in each pot for the big and small size seeds, and replicated thrice on 3rd, February 2012. Watering was done daily. Speed of germination was calculated using the formula: - A1+A2.../A1T1+A2+T2... × 100/1 Where A= number of seeds germinating, T= time (day) corresponding to germination Germination efficiency was observed in order to determine the rate of germination for both the big and small seeds of each variety of cowpea. Germination percentage was based on the total number of germinated seeds/total number planted seeds x100. The efficiency of seeds was expressed as the activation value (the reciprocal of a half time value) multiplied by the germination percentage i.e. 1/T50 × germination %. Average stem heights of three (3) seedlings of each treatment of the four varieties were recorded. The distance between ground level and the top of the main stem was taken as the stem height, using a metre rule on weekly basis. Leaf area was determined by multiplying the average leaf length, average leaf breath and 0.75 (i.e. L × B × 0.75). This was done biweekly. Number of leaves was determined by direct counting of the leaves on weekly basis Fresh and dry weights of seedlings from each of the varieties were also determined. The seedlings were dried in Gallenkemp oven, then the dry weight of the seedlings was taken for each variety and treatment (big and small seeds) on an electronic mettler balance, and the average was recorded. The day to flowering of the cowpea plants of both the big and small seeds of each variety was recorded. The seeds produced by cowpea plants from big and small seeds of each variety were dried after harvesting, and the average weight of 40 seeds was taken and recorded.

3. Results Seed size did not negatively affect germination speed in cowpea as both big and small seeds germinated readily with small seeds of both oloyin and Ifebrown faster than the big seeds 66.67, 66.67, 57.89 and 57.89% respectively (Figure 2). Germination efficiency was also better in both big and small seeds in all the varieties (Figure 3). 3.1. Number of Leaves: Number of leaves increased with age irrespective of the varieties and planting seed size. However, seedlings from big seeds produced more leaves than seedlings from small seeds (Table 2) The seedlings of small seeds of Ifebrown variety had the lowest number of leaves at 2WAP to 6WAP, but later had more leaves such that there was no significant difference in its number of leaves, when compared with seedlings of big and small seeds of drum and white varieties at 8WAP. 3.2. Stem height: Stem height also increased with age irrespective of the varieties, at 2WAP. But significant difference occurred by 3WAP, with seedlings of big seeds of the white variety having the tallest height from 3WAP to 8WAP (Table 3). Seedlings of small seeds of oloyin variety had the shortest height (Table 3.) 3.3. Leaf length: leaf length increased with age irrespective of the variety of cowpea. Significant difference in the leaf length occurred only at 2WAP. The seedlings had no significant difference in leaf length as from 4WAP to 8WAP. Probably, they have limits to rate of increase in leaf length. At 2WAP, there was significant difference in leaf length with seedlings of big seeds of drum variety had the longest leaf, while seedlings of small seeds of Ifebrown had the shortest leaf (Table 4.) 3.4. Leaf breadth: leaf breadth also increased with age irrespective of the varieties. Significant difference occurred in the leaf breadth at 2WAP and 8WAP, while there were no significant differences at 4WAP and 6WAP (Table 5).

390

Seed Size Influence On Germination And Seedling Development Of Cowpea (Vigna unguiculata (L) walp)

seeds of drum (38days) variety and the longest those from the small seeds of Ifebrown variety (52days). The table also reveals that, the flowering day of the cowpea plants of the big and small seeds of each variety differed.

Seedlings of big seeds from white cowpea variety had the widest leaf breath. Interestingly seedlings from big seeds of Ifebrown variety had leaf breadth that were not significantly different from those of the big seeds of the drum variety (Table 5).

4. Discussion

3.5. Leaf area: leaf area increased with age irrespective of the varieties. No significant differences occurred at 4WAP and 6WAP, but there were significant differences at 2WAP and 8WAP (Table 6). Table 6 also shows that, at 2WAP, the seedlings of big seeds from Drum had the highest value for leaf area while at 8WAP cowpea plants from big seeds of white variety had the highest value for leaf area. The seedlings with the lowest value for leaf area at 8WAP were those of oloyin variety. Though, no significant difference occurred in the leaf area of seedlings of its big and small seeds.

Results obtained from this study clearly showed that both seed size and seed weight played important role in seed germination, seedling vigour, vegetative growth and reproductive behaviour of cowpea. These observations agreed with the earlier reports of [8, 9] who observed significant effects of big and heavy seeds on the seedling dry weights and leaf area of Daniellia oliveri and production of more number of seedlings per seed, longer stem heights, higher seedling dry weights and more number of leaves from heavy seeds of Mangifera indica. Better performance of seedlings from big cowpea seeds may be as a result of greater vigour of seedlings after germination due to large amount of food reserves in those seeds that were readily made available to them. Similar observation was reported by [6] who reported better survival and greater dry matter yield in seedlings from heavy seeds than those from small seeds in Quercus semiserrata Roxb. Reduction in the germination percentage in small seeds of oloyin and drum cowpea in this study was in concord with the observation of [1] and [12] who variously reported that the germination percentage significantly declined with reduction in size and weight of the seeds of Alangium lamarckii and Prunus jenkinsii respectively.

3.6. Dry weight: Dry weight also increased with age irrespective of the varieties. Table 8 reveals that the dry weights of the seedlings of small seeds of Ifebrown had the least dry weights at 2, 4, and 6WAP while the seedlings of the big seeds of the local white varieties had the highest dry weights at 6WAP. However, at 2 and 4 WAP, the seedlings of the big seeds of the white variety had the highest dry weights. 3.7. Flowering: As shown on Table 9, the day to flowering of cowpea plants were shorter in cowpea plants from big

Figure1: Effect of seed size on germination rate of cowpea varieties

391

Ehoniyyotan and Olorunmaiye

Figure 2: Effect of seed s size on sppeed of germinnation of cow wpea varieties

Figure 3: Effect of seed s size on geermination effficiency of cowpea varieties Table 1: 1 Weight of 100 1 seeds of cowpea c varietiies planted (g)) Cowpea Seeeds Drum White Oloyinn Ifebrow wn

Size Big S Small Big S Small Big S Small Big S Small

W Weight of 100SSeeds (g) 28.099 15.022 26.300 14.722 20.288 13.055 13.666 7.50

392

Weiight of a seed (g) 1.40 0.75 1.32 0.74 1.02 0.65 0.68 0.38

Seed Size Influence On Germination And Seedling Development Of Cowpea (Vigna unguiculata (L) walp) Table 2: Effect of seed size on number of leaf of cowpea varieties Seed variety

Size 2WAP 3WAP 4WAP 5WAP 6WAP b abc cd cd Big 5.00 11.00 16.00 20.00 23.33cd Ifebrown b c d d Small 5.00 9.00 14.00 17.00 19.00d ab abc bc b Big 6.00 11.00 19.00 25.00 27.00ab Oloyin b abc bc c Small 5.00 11.00 19.00 24.00 26.00bc Big 8.00a 13.00a 23.00a 26.00b 26.00bc Drum ab bc bc c Small 6.00 10.00 19.00 23.33 25.00bc ab ab ab a Big 7.33 11.67 21.33 27.33 30.67a White Small 7.00ab 12.00ab 18.67bc 23.00c 27.00ab Values having the same letter(s) along the same column are not significantly different at (p < 0.05). WAP= week(s) after planting

7WAP 31.67a 27.00a 32.00a 29.67a 36.67a 36.00a 40.33a 39.00a

8WAP 50.67ab 40.33b 33.33b 29.67c 40.33b 41.67a 69.33a 47.37b

Table 3: Effect fo seed size on stem height of cowpea varteties Seed Variety Ifebrown

Size 2WAP 3WAP 4WAP 5WAP 6WAP 7WAP 8WAP a ab abc bc bc a Big 9.57 12.40 16.00 18.87 21.40 22.90 23.50ab a b cd de cd b Small 9.43 11.60 13.40 15.60 17.87 19.00 19.83bcd a b abc cd de b Oloyin Big 8.73 10.57 14.87 16.37 17.63 17.93 17.97de Small 7.80a 9.53c 11.17d 12.53e 14.13e 14.57c 15.67e a b ab b b a Drum Big 9.70 12.10 17.07 20.90 22.90 22.90 22.90abc a b bc de cd b Small 9.67 11.90 14.07 15.40 18.17 18.97 19.30cde White Big 8.27a 15.20a 19.57a 22.97a 25.20a 25.60a 26.33a a b abc cd bcd a Small 8.07 11.07 14.80 17.40 20.70 22.63 23.63ab Values having the same letter(s) along the same column are not significantly different at (p < 0.05). WAP= week(s) after planting Table 4: Effect of seed size on leaf length of cowpea varieties Seed Variety

Size 2WAP 4WAP 6WAP Big 5.77ab 8.43a 8.50a Ifebrown b a Small 4.70 6.03 8.00a Big 6.60ab 9.43a 10.17a Oloyin ab a Small 5.70 8.93 9.00a ab a Big 6.40 9.73 11.47a White Small 5.80ab 9.27a 9.53a a a Big 7.30 9.27 11.37a Drum ab a Small 6.87 10.43 10.93a Values having the same letter(s) along the same column are not significantly different planting

8WAP 11.63a 10.83a 10.17a 9.90a 12.27a 10..90a 12.47a 12.13a at (p < 0.05). WAP= week(s) after

Table 5: Effect of seed size on leaf breadth of cowpea varieties Seed variety Ifebrown

Size 2WAP 4WAP 6WAP 8WAP ab a a Big 3.17 4.90 5.27 7.63ab b a a Small 2.30 3.10 4.57 6.33bc ab a a Oloin Big 3.27 4.67 5.57 5.57c Small 3.10ab 4.40a 4.83a 5.90bc a a a White Big 4.17 5.57 7.83 8.47a ab a a Small 2.40 4.37 5.63 6.00bc Drum Big 4.07ab 5.57a 6.57a 7.73ab ab a a Small 3.13 5.23 6.67 7.23abc Values having the same letter(s) along the same column are not significantly different at (p < 0.05). WAP= week(s) after planting

393

Ehoniyotan and Olorunmaiye Table 6: Effect of seed size on leaf area (cm2) of cowpea varieties Seed variety

Size 2WAP 4WAP 6WAP 8WAP ab a a Big 14.24 31.67 37.81 68.26ab Ifebrown b a a Small 8.26 14.95 29.63 52.56ab ab a a Big 16.49 33.82 43.06 43.06b Oloyin ab a a Small 13.65 31.79 32.85 44.09b Big 20.70ab 42.39a 71.39a 78.65a White ab a a Small 10.58 32.15 43.86 49.59ab a a a Big 23.30 43.45 60.14 72.97ab Drum Small 16.87ab 42.51a 55.77a 66.11ab Values having the same letter(s) along the same column are not significantly different at (p < 0.05). WAP= week(s) after planting Table 7: Effect of seed size on cowpea dry weight (g)

Seed variety

Size 2WAP 4WAP 6WAP Big 0.27g 0.73g 3.23f Ife brown Small 0.18h 0.42h 1.40h f c Big 0.38 1.20 3.33e Oloyin e e Small 0.29 0.97 2.33g b b Big 0.60 1.55 6.67a Local white Small 0.40d 0.98d 3.67d a a Big 0.76 1.63 5.67b Drum c f Small 0.47 0.88 4.33c Values having the same letter(s) along the same column are not significantly different at (p < 0.05). WAP= week(s) after planting Table 8: Effect of seed size on the dry weight of cowpea seedlings (g) SeedVariety

Size 2WAP 4WAP 6WAP Big 0.27g 0.73g 3.23f Ifebrown b b Small 0.18 0.42 1.40h Big 0.38f 1.20c 3.33e Oloyin e e Small 0.29 0.97 2.33g b b Big 0.60 1.55 6.67a White d d Small 0.40 0.98 3.67d Big 0.76a 1.63a 5.67b Drum c f Small 0.47 0.88 4.33c Values having the same letter(s) along the same column are not significantly different at (p < 0.05). WAP= week(s) after planting Table 9: Effect of seed size on the reproductive performance of cowpea varieties Seed variety Ifebrown Oloyin White Drum

Size Big Small Big Small Big Small Big Small

Day to flowering 49 57 41 43 49 52 38 44

Number of seed per pod 11.8 10 10 9.8 11 10.7 8.7 12

germination percentage and seedling vigour over small seeds. In some cases however, small seeds showed faster germination speed due to faster and

5. Conclusion Results and observations from this study revealed that big seeds of cowpea had advantage of higher

394

Seed Size Influence On Germination And Seedling Development Of Cowpea (Vigna unguiculata (L) walp)

higher water absorption in the early stage of germination.

seed size and NaCl on germination and early seedling growth of some Turkish cultivars of chickpea (Cicer arietinum L.) J. Zhejiang Univ Sci B. May 2008, 9(5): 371–377.

6. References

8. Olorunmaiye KS, Olorunmaiye PM and Fatoba PO: The effects of planting orientation and seed attributes on germination and seedling development of Daniellia oliveri (Rolf). Hutch and Dalz.The Biological and Environmental Sciences Journal for the tropics (BEST) 2010, Vol.7 (2): 146-150

1. Ahirwar JR: Effect of seed size and weight on seed germination of Alangium lamarckii, Akola, India. Research Journal of Recent Sciences 2011, Vol. 1(ISC-2011), 320-322 . 2. Coetzee JJ: Cowpea; a traditional crop in Africa. Sayce E.N publishing Devon, U.K. 1995 3. Creamer NG and Baldwin KR: An evaluation of summer cover crops for use in vegetable production in North Carolina.Hortscience 2000, 35(4): 600-603.

9. Olorunmaiye KS, Fatoba PO, Olorunmaiye PM and Adeyemi C OreOluwa: Seed weight and Morpho-physiological parameters in Mango (Mangifera indica) seedlings. Pomologia Croatica 2011, 17 (3-4): 77-86. Published by Croatian society of agronomist Berislavićeva 6, Zagreb. http://www.agronomsko.hr

4. Davis DW, Oelke EA, Hanson CV, Putnam DH, Oplinger ES and Doll JD: Alternative field manual. University of Wisconsin, Madison Wisconsin/University of Minnesota 1991

10. Singn SP and Rai PN: Effect of seed size upon germination and early stages of plant growth of cowpea, IHSA Acta 1988, 218: 71-76. Available at Http// www.actahort.org/books/218/218-9.htm.

5. James Q: Cowpea a versatile legume for hot, dry condition, published by Jefferson institute, Columbia 1999, M.O 3/99, Indiana edition.

11. Ton E and Koop W: Guide to cultivated plants. CABI publisher, Wallingford U.K 2008, Pg. 256261.

6. Khan ML and Shankar U: Effect of seed weight, light regime and substratum microsite on germination and seedling growth of Quercus semiserrata Roxb. Tropical Ecology 2001, 42 (1): 117-125. International Society for Tropical EcologyM.L. 7.

12. Upadhaya K, Pandeh HN and Law PS: The Effect of Seed Mass on Germination, Seedling Survival and Growth in Prunus jenkinsii Hook.f. & Thoms. Turk J Bot 2007, 31: 2007 3136

Kaya M, Kaya G, Kaya D, Atak M, Saglam S, Khawar KM and Ciftci CY: Interaction between

395